Thor-Agena Launch Vehicle Family

Thor-Agena was a family of expendable launch vehicles that paired Douglas Thor-derived first stages with Lockheed Agena upper stages. Beginning with Discoverer 1 in 1959, successive short-tank, thrust-augmented, and long-tank configurations supported reconnaissance, meteorology, geophysics, navigation, and geodesy missions from the Western Test Range. The lineage progressed from Agena A through restartable Agena B and standardized Agena D upper stages.